Radiative penguins at hadron machines. Kevin Stenson! University of Colorado!

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1 Radiative penguins at hadron machines Kevin Stenson! University of Colorado!

2 Introduction γ + b q u,c,t W s q b q u,c,t W + s q b q ν W W + u,c,t s q!! Radiative penguins involve b to s,d transitions with a radiated photon (b!s".!! b!sll also contain an electroweak box diagram.!! Highly suppressed in standard model but new physics can add particle to loop, changing the decay rate or details of the decay. Kevin Stenson Radiative penguins at hadron machines

3 Results from LHC: ATLAS, CMS,!! ATLAS and CMS are general purpose experiments covering the central region (designed for high-p T physics!! is a dedicated b-physics experiment covering the forward region. Kevin Stenson Radiative penguins at hadron machines 3

4 B!K* " and B s!#" from!! Trigger requires EM energy cluster of E T >.5, followed by requiring a displaced tracks and then requiring two tracks to match K*!K + $ % or &!K + K %, with a B mass within 1 GeV of nominal.!! Offline requirements similar to trigger plus particle ID from RICH and a helicity cut to reduce $ contribution.!! Fit to B mass includes contributions from subdominant partially reconstructed b!s" and charmless decays Candidates / 5 MeV/c with $. 1 (a 1 Nucl. Phys. B 867 (1 18 Candidates / 5 MeV/c (b Candidates /.5 MeV/c Candidates /.65 MeV/c (a M(Kπ (MeV/c (b M(K + K - (MeV/c M(K (MeV/c M(K 55 K 6 (MeV/c Kevin Stenson Radiative penguins at hadron machines

5 b!s" decays at a hadron machine!!! From the yields, efficiencies, and the measurement of f s /f d (the production ratio of B s to B d, the following ratio is measured:!! The B!K* " sample is split into particle and antiparticle to search for direct CP violation.!! After correcting for production related effects, material related effects, and detector related effects, no asymmetry is found: Candidates / 5 MeV/c (a Candidates / 5 MeV/c (b Full fit * B d K Combinatorial,+ * B K,+ B V X M(K 55 + (MeV/c M(K 55 (MeV/c 6 Kevin Stenson Radiative penguins at hadron machines 5-5 5

6 Reconstructing B +!K + µ + µ % at!! Triggered by muon with p T >1.5 GeV, a displaced track, and requirements based on partial or full reconstruction of B +.!! Offline: cuts and BDT based on standard criteria (vertex fit quality, vertex displacement, momentum point-back, impact parameters, etc. and neural network for particle ID. Candidates / [5 MeV/c ] Peaking background Combinatorial background m K + µ + µ - [MeV/c ]!! Decay described by one angle, ' l, plus q =m (µµ. Analysis fits cos' l and B + mass in bins of q to obtain the yield and two parameters related to the decay: F H and A FB. Kevin Stenson Radiative penguins at hadron machines 6

7 ]! c /GeV.6 Results for B +!K + µ + µ % decay Theory Binned theory CDF BELLE BaBar A FB 1.5 CDF BELLE -7 [1. db/dq q [GeV /c ] results are by far the most precise. Small deviation in branching fraction at low q. The forwardbackward asymmetry is consistent with as expected. The F H parameter, measured for the first time, is also consistent with the SM. F H Theory Binned theory q [GeV /c ] JHEP 13 ( [GeV /c ] Kevin Stenson Radiative penguins at hadron machines 7 q

8 B!K* µ + µ % decay!! The kinematics of the B!K* µ + µ % decay are described by three angles (' K, ' L, & plus the q of the decay = m (µµ.!! is usually binned in q and fitted to the angular variables.!! Full theoretical description of decay is below: d Γ dq dcos θ K dcos θ dφ = 9 3π Kevin Stenson Radiative penguins at hadron machines 8! +!! #L S s 1 sin θ K + S c 1 cos θ K + $ B K +!! / K* S s sin θ K cos θ + S c cos θ K cos θ + S 3 sin θ K sin θ cos φ + S sin θ K sin θ cos φ + S 5 sin θ K sin θ cos φ + S 6 sin θ K cos θ + S 7 sin θ K sin θ sin φ + S 8 sin θ K sin θ sin φ + S 9 sin θ K sin θ sin φ #K "!

9 d Γ dq dcos θ K dcos θ dφ = 9 3π Terms cancel when # is folded B!K* µ + µ % decay S s 1 sin θ K + S c 1 cos θ K + S s sin θ K cos θ + S c cos θ K cos θ + S 3 sin θ K sin θ cos φ + S sin θ K sin θ cos φ + S 5 sin θ K sin θ cos φ + S 6 sin θ K cos θ + S 7 sin θ K sin θ sin φ + S 8 sin θ K sin θ sin φ + S 9 sin θ K sin θ sin φ d Γ dq dcos θ K dcos θ dφ = 9 F L cos θ K π (1 F L 1 cos θ K For q»m µ : F L = S c 1 = %Sc 1%F L = (S s 1 = Ss A FB = %(S 6 S 9!A 9 when #!%# for anti-b ; A 9 is better for CP-asymmetries. F L cos θ K cos θ (1 F L 1 cos θ K cos θ 1 + Kevin Stenson S 3 1 cos θ K 1 cos θ cos φ + 3 A FB 1 cos θ K cos θ + A 9 1 cos θ K 1 cos θ sin φ With the assumptions of large q and folding the # distribution, expression simplifies to free parameters. fits this equation while other experiments integrate over # to simplify further. Radiative penguins at hadron machines 9

10 Events / MeV Events / 3 MeV 18 ATLAS Preliminary s = 7 TeV 16. GeV < q <.3 GeV Ldt =.9 fb Reconstructing B!K* µ + µ % The B candidate is composed of four charged tracks: K +, $ %, µ +, µ %. Backgrounds are reduced by requiring a good vertex, displaced from the production points and with a momentum vector consistent with the production point. Also, explicit cuts on backgrounds (like B s!#µ + µ %. Below are B!K* µµ invariant mass plots from the 3 experiments for the smallest common q bin (top and largest q bin (bottom Y=19±8! " fit Background fit m(k!µµ [MeV] ATLAS Preliminary s = 7 TeV 16. GeV < q < 19. GeV Ldt =.9 fb " fit Background fit Y=19±! m(k!µµ [MeV] Events / (.8 GeV/c Events / (.8 GeV/c CMS preliminary!1 L = 5. fb s = 7 TeV q :.!.3 GeV /c yield: 5. ± M(K "! µ + µ! (GeV/c Y=5±9! CMS preliminary Y=13±1! Kevin Stenson Radiative penguins at hadron machines 1 Comb. bkg M(K "! µ + µ! (GeV/c!1 L = 5. fb s = 7 TeV Comb. bkg q : 16.! 19. GeV /c yield: 13.1 ± 1. Candidates / ( 1 MeV/c Candidates / ( 1 MeV/c 6 6 < q <.3 GeV /c !! m(k " µ + µ [MeV/c ] 16 < q Y=73±11! < 19 GeV /c Y=116±13! !! m(k " µ + µ [MeV/c ]

11 : Fitting the B!K* µ + µ % decay d Γ dq dcos θ K dcos θ dφ = 9 16π D fit to cos' K, cos' l, #, and invariant mass in q bins to get F L, A FB, S 3, A 9. 1D mass fit for yield used in branching fraction. CMS: ATLAS: CMS-PAS-BPH1-9 F L cos θ K + 3 (1 F L 1 cos θ K F L cos θ K cos θ (1 F L 1 cos θ K cos θ 1 + S 3 1 cos θ K 1 cos θ cos φ + 3 A FB 1 cos θ K cos θ + A 9 1 cos θ K 1 cos θ sin φ 3D fit to cos' K, cos' l, and invariant mass in q bins to get F L and A FB. plus 1D mass fit for yield used in branching fraction. S-wave contribution included in fit (with values for F S and A S taken from B!J/K*. d 3 Γ = 9 dq dcos θ K dcos θ 16 3 F S A S cos θ K cos θ + (1 F S F L cos θ K 1 cos θ + 1 (1 F L 1 cos θ K 1 + cos θ + 3 A FB 1 cos θ K cos θ d Γ = 3 dq dcos θ F L 1 cos 3 θ + 8 (1 F L 1 + cos θ + AFB cos θ 1D fit to invariant mass to get signal and dq dcos θ background yields and shapes. K 3D fit to cos' K, cos' l, and invariant mass done using independent description of two angles. Obtain results for F L and A FB. ATLAS-CONF3-38 Kevin Stenson Radiative penguins at hadron machines 11 d Γ arxiv: = 3 F L cos θ K + 3 (1 F L 1 cos θ K

12 Events / (. Fitting the B!K* µ + µ % decay Projections of fits to angular variables look reasonable. Differences between ATLAS and CMS may be from cuts or angle definitions. CMS preliminary 6 q : 1. " 6. GeV /c 5 "1 L = 5. fb s = 7 TeV Comb. bkg Events / (. CMS preliminary 6 q : 1. " 6. GeV /c 5 "1 L = 5. fb s = 7 TeV Comb. bkg cos(! K cos(! l Events /. 5 ATLAS Preliminary s = 7 TeV 1. GeV < q " < 6. GeV Ldt =.9 fb 35 fit Background fit 3 5 Events / ATLAS Preliminary s = 7 TeV 1. GeV < q < 6. GeV " Ldt =.9 fb fit Background fit cos! K Kevin Stenson Radiative penguins at hadron machines 1 cos! L

13 B!K* µ + µ % branching fraction!! The branching fraction measurement for B!K* µ + µ % utilizes the normalization mode B!J/ K*. The ratios of yields are corrected by ratios of efficiencies and the PDG value of the B!J/ K* branching fraction is used to obtain an absolute rate.!! Results are consistent with standard model.! ( GeV/c "!7 ( 1 dbf/dq SM CMS BaBar Belle CDF q ( GeV/c Kevin Stenson Radiative penguins at hadron machines 13

14 F L from B!K* µ + µ %!! The fraction of longitudinally polarized K* mesons in the decay is extracted from the fit.!! The 3 LHC based results are more precise than the b-factory results.!! Taken as a whole, no indication of deviation from the standard model. Note the theory and experimental uncertainties are comparable. F L SM CMS Atlas BaBar Belle CDF q ( GeV/c Kevin Stenson Radiative penguins at hadron machines 1

15 A FB from B!K* µ + µ %!! The forward-backward asymmetry of the two muons in the decay is extracted from the fit.!! The 3 LHC based results are more precise than the b-factory results.!! No indication of deviation from the standard model.!! In addition, measures the location of the crossing point to be.9±.9 GeV, consistent with the standard model. A FB SM CMS Atlas BaBar Belle CDF q ( GeV/c Kevin Stenson Radiative penguins at hadron machines 15

16 Other angular analysis results from B!K* µ + µ %!! From the fit to all three angles, extracts two other parameters related to the decay, S 3 and A 9.!! These also don t show indications of new physics (yet. Theory Binned S 3. A q [GeV /c ] q [GeV /c ] Kevin Stenson Radiative penguins at hadron machines 16

17 A CP F L S Uncovered results (all from a b B!K* µ + µ %! q q [GeV /c ] q [GeV A 6 A 9 /c ] [GeV c d /c ] A I B K!! q [GeV /c ] q [GeV /c ] q [GeV m( e + e K * B s!#µ + µ %! [MeV/ Kevin Stenson Radiative penguins at hadron machines 17 /c ] Candidates / (5 MeV/c A I Theory * + - B K!! q HWElectron [GeV /c ] Covered by Marc-Olivier Bettler on Monday c ]

18 Summary and outlook!! Results from the LHC experiments, especially, have eclipsed the b-factories in some very important areas of radiative penguin decays, most notably in B!K* µ + µ %.!! Unfortunately, new physics has not yet been found.!! Results shown here are from 11 data taking (about 1 fb for and about 5 fb from ATLAS/CMS.!! The 1 data provide an additional fb for and fb for ATLAS/CMS. Should allow for more decay modes (such as * b!*µ + µ %, better precision on existing decay modes, and checking more variables in existing decay modes.!! The hunt for new physics continues+ Kevin Stenson Radiative penguins at hadron machines 18

19 Backup Kevin Stenson Radiative penguins at hadron machines 19

20 B!K* µ + µ % efficiencies from CMS Efficiencies versus q (integrated over angles and versus cos' K, cos' L, and # (in bins of q. Representative only; D functions in (cos' K,cos' L used for efficiency parameterization in likelihood fit. Kevin Stenson Radiative penguins at hadron machines

21 Effect of S-wave on B!J/K* distributions No allowance for S-wave in fit S-wave allowed in fit Kevin Stenson Radiative penguins at hadron machines 1

22 B!K* µ + µ % mass plots from ATLAS Events / MeV 18 ATLAS Preliminary s = 7 TeV 16. GeV < q <.3 GeV Ldt =.9 fb " fit Background fit Events / MeV 7 ATLAS Preliminary s = 7 TeV.3 GeV < q < 8.68 GeV Ldt =.9 fb 6 " 5 fit Background fit m(k!µµ [MeV] m(k!µµ [MeV] Events / 17 MeV 35 ATLAS Preliminary s = 7 TeV 1.9 GeV < q < 1.86 GeV Ldt =.9 fb " fit Background fit Events / 7 MeV ATLAS Preliminary s = 7 TeV 1.18 GeV < q < 16. GeV Ldt =.9 fb " fit Background fit Events / 3 MeV 5 3 ATLAS Preliminary s = 7 TeV 16. GeV < q < 19. GeV Ldt =.9 fb " fit Background fit m(k!µµ [MeV] m(k!µµ [MeV] m(k!µµ [MeV] Events / MeV ATLAS Preliminary s = 7 TeV 1. GeV < q < 6. GeV Ldt =.9 fb " fit Background fit Contributions from radiative tail of charmonium modes removed using cut of: m B m B rec PDG m µ + µ m (J/ψ rec PDG < 13 MeV 15 1 and similar cut for (S Kevin Stenson m(k!µµ [MeV] Radiative penguins at hadron machines

23 B!K* µ + µ % mass plots from CMS CMS preliminary!1 L = 5. fb s = 7 TeV CMS preliminary!1 L = 5. fb s = 7 TeV CMS preliminary!1 L = 5. fb s = 7 TeV Events / (.8 GeV/c Comb. bkg q : 1.!. GeV /c yield: 3. ± 6.3 Events / (.8 GeV/c Comb. bkg q :.!.3 GeV /c yield: 5. ± 8.8 Events / (.8 GeV/c Comb. bkg Peak. bkg q :.3! 8.68 GeV /c yield: 9. ± M(K "! µ + µ! (GeV/c M(K "! µ + µ! (GeV/c M(K "! µ + µ! (GeV/c CMS preliminary!1 L = 5. fb s = 7 TeV CMS preliminary!1 L = 5. fb s = 7 TeV CMS preliminary!1 L = 5. fb s = 7 TeV Events / (.8 GeV/c 5 3 Comb. bkg Peak. bkg q : 1.9! 1.86 GeV /c yield: 95.7 ± 15.6 Events / (.8 GeV/c Comb. bkg Peak. bkg q : 1.18! 16. GeV /c yield: 58. ± 1.1 Events / (.8 GeV/c Comb. bkg q : 16.! 19. GeV /c yield: 13.1 ± M(K "! µ + µ! (GeV/c M(K "! µ + µ! (GeV/c M(K "! µ + µ! (GeV/c CMS preliminary!1 L = 5. fb s = 7 TeV Events / (.8 GeV/c 5 3 Comb. bkg q : 1.! 6. GeV /c yield: 17. ± Kevin Stenson Radiative penguins at hadron machines + M(K "! µ + µ! (GeV/c

24 Candidates / ( 1 MeV/c 6 B!K* µ + µ % mass plots from.1 < q < GeV /c Combinatorial bkg Peaking bkg Candidates / ( 1 MeV/c 6 < q <.3 GeV /c Candidates / ( 1 MeV/c 6.3 < q < 8.68 GeV /c Candidates / ( 1 MeV/c !! m(k " µ + µ [MeV/c ] 1.9 < q < 1.86 GeV /c Candidates / ( 1 MeV/c !! m(k " µ + µ [MeV/c ] 1.18 < q < 16 GeV /c Candidates / ( 1 MeV/c !! m(k " µ + µ [MeV/c ] 16 < q < 19 GeV /c !! m(k " µ + µ [MeV/c ] !! m(k " µ + µ [MeV/c ] !! m(k " µ + µ [MeV/c ] [MeV/c ]! m(! +! Charmonium decays (including misreconstructed and with soft photons are removed by applying cut including information on K$µµ mass Kevin Stenson +!! m(k "! [MeV/c Radiative penguins at hadron machines +! ]

Studies of rare B meson decays with the CMS detector

Studies of rare B meson decays with the detector J.Pazzini on behalf of the Collaboration Padova University & INFN - August - 3 J.Pazzini Studies of rare B meson decays with the detector (SUSY3) Introduction